超大断面矩形顶管土体扰动分析及沉降控制

Soil Disturbance Analysis and Settlement Control of Rectangular Pipe Jacking with Super Large Section

研究目的:超大断面顶管施工土体扰动及沉降控制对整个工程风险控制至关重要,为探究超大断面矩形土压平衡顶管土体扰动规律及沉降控制方法,以郑州红专路下穿中州大道顶管工程为依托,通过顶管模型及土体沉降数值解分析,深入分析顶管过程参数对土体变形影响规律。研究结论:(1)矩形顶管不同因素作用下土体沉降影响数值解同实测数值较一致,验证了数值模型解的准确性;(2)通过对土体扰动影响因素进行分析,泥皮套摩阻系数对地层沉降影响较小,推力、注浆压力适当增大可抑制地表沉降,建议推力略大于1倍掌子面中心土压力,注浆压力控制在2倍上覆土层压力以内;(3)装备防背土设计、管节涂蜡、触变泥浆、渣土改良、注浆减摩等手段综合应用对减少大断面顶管土体扰动及沉降控制效果显著;(4)本研究成果可为超大断面矩形土压平衡顶管工程提供参考或借鉴。

Research purposes:The soil disturbance and settlement control in the construction of super-large section pipe jacking is very important to the risk control of the whole project.In order to explore the soil disturbance law and settlement control method of super-large section rectangular earth pressure balance pipe jacking,based on the pipe jacking project of Zhengzhou Hongzhuan Road crossing Zhongzhou Avenue,through the pipe jacking model and numerical solution analysis of soil settlement,the influence law of pipe jacking process parameters on soil deformation is deeply analyzed.Research conclusions:(1)The numerical solution of soil settlement under different factors of rectangular pipe jacking is consistent with the measured value,which verifies the accuracy of the numerical model solution.(2)Through the analysis of the influencing factors of soil disturbance,it is found that the friction coefficient of mud jacket has little influence on the ground settlement,and the proper increase of thrust and grouting pressure can inhibit the ground settlement.It is suggested that the thrust should be slightly greater than 1 time of the central earth pressure of the face,and the grouting pressure should be controlled within 2 times of the overlying soil pressure.(3)The comprehensive application of anti-back soil design,pipe joint wax coating,thixotropic mud,slag improvement,grouting and friction reduction,has a significant effect on reducing soil disturbance and settlement control of large-section pipe jacking.(4)The research results can provide reference for super-large section rectangular earth pressure balance pipe jacking engineering.